The present invention relates to a spindle or drum sander, and more particularly, to an oscillating spindle sander tool employing a combined motor and mechanical drive that provides both rotary and reciprocal or axial movement to the spindle, thus providing the oscillating movement desired for spindle sanders. The combined motor and mechanical drive has other applications, as well.
Spindle sanders, when viewed from the exterior, appear to be very simple mechanisms. All that an untrained viewer can see is an enclosed frame with a horizontally extending worktable through which a vertically extending spindle sander projects. When the spindle sander is operated, the viewer can readily see that the spindle sander both rotates as well as reciprocates or moves in an axial path. This would suggest to the viewer that there is something more than expected within the enclosed frame to provide the simultaneous rotary and reciprocal or axial movement of the spindle sander.
Those skilled in the art are immediately aware of the costly and complex mechanisms that have been required for producing the simultaneous rotary and reciprocal or axial movement of the spindle sander. Typically, such mechanisms include pulleys, cylinders, cams, gears and the like which are constructed in various arrangements and which operate in conjunction with an electrical motor to produce the simultaneous bi-directional movement desired. Prior art spindle sanders have also required the use of a spindle shaft separate from the motor shaft. As is also well known by those skilled in the art, the complex prior art arrangements not only add substantial cost to oscillating spindle sanders, but also increase the likelihood of a malfunction due to the substantial number of moving parts that are required.
The prior art has long recognized the need for a reliable, efficient and cost effective mechanism which produces simultaneous rotary and reciprocal or axial movement for use in such applications as oscillating spindle sanders. As will be apparent from the detailed discussion that follows, the present invention overcomes many of the complex and costly mechanisms employed in prior art devices.